Pallet Jacks, both manual and motorized, are used to move objects and loads that are often stacked on pallets. Pallet jacks are typically comprised of a fork shaped lifting structure, two front lifting wheels, a rear wheel, a rotatable operating handle and a hydraulic assembly connecting the handle to the fork structure. The pallet jack assembly provides the ability to lift a load from the ground, the safe transport of the load to a desired location, and to return the load to the ground. Some pallet jacks have rear left and right casters for improved stability.
With manually operated pallet jacks, the user applies a force to the rotatable rear handle causing movement of the overall pallet jack and load. After a user places the pallet jack under a desired load, the user raises and lowers the handle which is connected to a hydraulic cylinder. The hydraulic cylinder moves mechanical linkages causing vertical displacement of the forks, and load, relative to the ground. The rotatable handle is then used to steer and move the load to the desired location. Most manual pallet jacks have a lift actuation lever mounted to the handle which releases the pressure in the hydraulic cylinder causing the load to safely return to the ground. Manual pallet jacks are well known in the art of material handling. They have widespread adoption and a low cost point.
Motorized pallet jacks are used for making it easier and potentially safer for the operator to move a load than with manual pallet jacks. Rather than relying on the force generated by the user to move the load, motorized pallet jacks have an electrical motor attached to the rear wheel making it a drive wheel. The torque from the electric motor provides forward and reverse translation of the pallet assembly. Attached to the rotatable handle is a second actuator that controls the direction and speed of the electric motor and pallet assembly. The operator steers the pallet the same as a manual version, via the rotatable rear handle. Lifting the load is most often done via a manual type hydraulic cylinder, or can be accomplished by connecting a pump or lift motor to the batteries of the electric drive motor. With the addition of batteries and controls, the drawback of existing motorized pallet jacks is that they are usual larger than manual versions and can cost substantially more to produce.
Remote controlled pallet jacks are used to move a load without physical interaction of a user. The user instructs the pallet jack via a handled controller, such as a mobile phone or pendant. The rear wheels of the jack are motorized for linear travel and steering is accomplished with an additional motor that spins the drive wheel assembly in the desired direction of travel. To raise the jack forks, yet another motor is used to actuate a hydraulic cylinder. Remote controlled pallet jacks are beneficial to user safety, but the additional motors of the prior art make them substantially large, expensive and complex.
Recently, fully automated pallet jacks have been developed. These systems use a computer system for guiding and controlling the overall assembly, thus eliminating the need for an operator. Automated material movers are most commonly referred to as Automated Guided Vehicles (“AVG”) as they look and perform more like a vehicle than a pallet jack. Their designs have been driven by large warehouse and “pick and ship” companies and thus are highly specialized. Although suitable for use in specialized facilities, they are too expensive and specialized to be used as replacement for manual and motorized pallet jacks in most applications.
In these respects, the present invention departs from conventional concepts of the prior art by providing a motorized, remote controlled, or automated pallet jack that can be used in existing manual pallet jack applications. The independently driven dual drive wheels, according to the present invention, provide the ability to move, steer and lift a load through the use of two motors. The present invention provides a more compact and low cost motorized pallet jack than the prior art.